Case #391 – March 2015

A lab in India received an arthropod specimen from a parent whose child had been suffering for about a week with rashes over his extremities and back. The patient was initially treated for the rashes, but they returned. Images of the organism were captured and sent to the DPDx Team for diagnostic assistance. Figures A and B show two of the images received. What is your identification? Based on what criteria? What is the public health importance, if any, of this organism?

Figure A

Figure B

The arthropod in this case was the human flea, Pulex irritans. Diagnostic morphologic features included:

a lack of both pronotal and genal combs.
mesopleuron not divided by a sclerotized rod.
ocular bristle (arrow, Figure B) located below the top of the eye.

Pulex irritans is primarily a nuisance pest. It is not an efficient vector of disease-causing agents but can serve as an intermediate host for the intestinal cestodes Dipylidium caninum, Hymenolepis nana, and H. diminuta.

Figure B